//关闭窗体
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (MessageBox.Show("确实要退出终端升级系统吗?", "终端升级系统", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                this.Dispose();
                Application.Exit();
            }
            else
            {
                e.Cancel = true;
            }
        }